The oxidative conversion of the N,S-bridged complexes [{RhLL'(μ-X)}2] to [(RhLL')3)(μ-X)2]+ (X = mt or taz): a comparison with the oxidation of N,N-bridged analogues

The structures of [{RhLL'(μ-X)}(2)] [LL' = cod, (CO)(2), (CO)(PPh(3)) or {P(OPh)(3)}(2); X = mt or taz], prepared from [{RhLL'(μ-Cl)}(2)] and HX in the presence of NEt(3), depend on the auxiliary ligands LL'. The head-to-tail arrangement of the two N,S-bridges is accompanied by a rhodium-eclipsed conformation for the majority but the most hindered complex, [{Rh[P(OPh)(3)](2)(μ-taz)}(2)], uniquely adopts a sulfur-eclipsed structure. The least hindered complex, [{Rh(CO)(2)(μ-mt)}(2)], shows intermolecular stacking of mt rings in the solid state. The complexes [{RhLL'(μ-X)}(2)] are chemically oxidised to trinuclear cations, [(RhLL')(3)(μ-X)(2)](+), most probably via reaction of one molecule of the dimer, in the sulfur-eclipsed form, with the fragment [RhLL'](+) formed by oxidative cleavage of a second.     

Pd(I) phosphine carbonyl and hydride complexes implicated in the palladium-catalyzed oxo process

Reduction of compound "Pd(bcope)(OTf)2" [bcope = (c-C8H14-1,5)PCH2CH2P(c-C8H14-1,5); OTf = O3SCF3] with H2/CO yields a mixture of Pd(I) compounds [Pd2(bcope)2(CO)2](OTf)2 (1) and [Pd2(bcope)2(mu-CO)(mu-H)](OTf) (2), whereas reduction with H2 or Ph3SiH in the absence of CO leads to [Pd3(bcope)3(mu3-H)2](OTf)2 (3). Exposure of 3 to CO leads to 1 and 2. The structures of 1 and 3 have been determined by X-ray diffraction. Complex [Pd2(bcope)2(CO)2](2+) displays a metal-metal bonded structure with a square planar environment for the Pd atoms and terminally bonded CO ligands and is fluxional in solution. DFT calculations aid the interpretation of this fluxional behavior as resulting from an intramolecular exchange of the two inequivalent P atom positions via a symmetric bis-CO-bridged intermediate. A cyclic voltammetric investigation reveals a very complex redox behavior for the "Pd(bcope)(OTf)2"/CO system and suggests possible pathways leading to the formation of the various observed products, as well as their relationship with the active species of the PdL2(2+)/CO/H2-catalyzed oxo processes (L2 = diphosphine ligands).     

Redox activation of a B-H bond: a new route to metallaboratrane complexes

Oxidative activation of a B-H bond of a coordinated scorpionate ligand provides an unprecedented route to rhodaboratranes.     

Salts of two pentahalo(N‐donor)­bismuthate(III) anions: [BiX5L]2− (X = Cl,Br; L = pyridine, 4‐picoline)

Two pentahalo(N‐donor)­bismuthate(III) salts, bis­[hydrogen bis(4‐picoline)(1+)] penta­bromo(4‐picoline‐N)bismuthate(III), (C₁₂H₁₅N₂)₂[BiBr₅(C₆H₇N)], (I), and bis­(pyridinium) penta­chloro­(pyridine‐N)­bismuthate(III), (C₅H₆N)₂[BiCl₅(C₅H₅N)], (II), are described which show modest deviations from octahedral geometry at bismuth. In (I), the cations comprise two 4‐picoline mol­ecules sharing a proton and in (II), pyridinium cations are present. The anion in (I) has twofold and that in (II) has mirror crystallographic symmetry. Both structures show a layered packing formed by the anions with the cations between the layers. Ring–ring interactions seem important in (I), whilst in (II), N/­C—H?Cl—Bi hydrogen bonding is abundant.     

Double Insertion of Coordinated Phosphanylalkyne Ligands into a Pt−C6F5 Bond

Enhanced reactivity is shown by uncoordinated C≡C bonds in the proximity of a metal in phosphanylacetylene complexes. cis-[Pt(C₆F₅)₂(thf)₂] reacts with [M(C₆F₅)₂(PPh₂C≡CPh)₂] (M=Pt, Pd) to form binuclear complexes containing the novel 2,3-bis(diphenylphosphanyl)-1,3-butadien-1-yl bridging ligand. Substitution of the solvent ligands with, for example, PPh₂H (see picture) provides species that could be characterized by X-ray crystallography.